Invading bug raising a stink across Oregon

Insome ways, it’s a race against time. It appears the potentially devastatingbrown marmorated stink bug is spreading in Oregon, and populations of the insectpest areexpected to jump over the next couple of years.

Meanwhile, research isunder way in Oregon and two other states centering on a tiny wasp, which happens to be anatural predator of the exotic stink bug, to seeif it can be an effectivebiological control agent.

In a best-case scenario, the good bug will be able to gointo battle about the same time the stink bug population takes off.

Oregonwants to avoid the extensive damage Pennsylvania and other states have suffered because of thebrown marmorated stink bug. What started out as a nuisance pest a decade ago inthe Mid-Atlanticstates has now exploded.

Pennsylvania has reported majorlosses the past couple of years for apples, peaches, grapes, tomatoes, and manyother fruits and vegetables that also grow in Oregon.

Thelist of crops andplants the stink bug won’t feed on is probably shorter than the list of cropsand plants it likes. The bug even feeds on maple and cedar trees.

Thebrown marmorated stink bug was first discovered in 2004 as a home pest inPortland. Additional sightings initially took place in urban areas. But the pastcouple of years, the bug has beenfound in such agricultural production areasas the Willamette Valley and Hood River.

In Central Oregon, there’s been only one detection of the brown marmorated stink bug in Deschutes County, but numerous finds in Jefferson County, said Oregon Department of Agriculture spokesman Bruce Pokarney.

“Apparently, several were found at a campground in Culver earlier this year,” Pokarney said.

“Ona pest risk scale of one to ten, I would say the brown marmorated stink bug isa 15,” says Helmuth Rogg, manager of the Oregon Department of Agriculture’sInsect Pest Prevention andManagement Program. “We don’t want to make it soundtoo alarming, but we want people to be aware that there is great potential forthis to be a very, very bad pest. Hopefully, time is on our sideand we canavoid the big outbreak we’ve seen in eastern states. Biological control canhelp.”

ODAis the lead regional agency for conducting research involvingTrissolcus halymorphae, the importedwasp that acts as a parasite of the brown marmorated stink bug.

ODA hasreceived$116,147 from the US Department of Agriculture as part of a Farm Billfunding package addressing pest and disease management. Florida and Michiganare the other two states looking at the samegood bug to treat the bad insectpest.

The tiny wasps were collected from Asia – also home to the brownmarmorated stink bug – and have been provided by USDA’s Agricultural ResearchService (ARS).Oregon was a good candidate for the funds because it has the pest tobegin with, ODA has the expertise in biological control, and Oregon StateUniversity has the quarantine facility needed to rearthe insects and house theresearch.

“It’sa perfect choice for a classical biological control program,” says Rogg. “Wehave an exotic pest that comes into a new environment without its naturalenemies where it can easilymultiply. Parasiticwaspsare found in its native Asia, brought to the US, and tested in the lab.Hopefully, biocontrol will be successful in controlling the brown marmoratedstink bug because there aren’t really anyother viable management options atthe moment.”

Ayear ago, ODA received permission to import the tiny good bugs– classified asparasitoids from the original ARS rearing facility in Delaware. The researchprogram set up shop at OSUwhere not only was a colony of parasitoidsestablished over the winter, but a colony of brown marmorated stink bugs aswell. Research confirmed that the adult female tiny wasp lays its eggs insidethe brown marmorated stink bug eggs. As a result of the parasitization, thestink bug egg does not survive.

Thebig concern, and the reason it is way too early to consider the biocontrolagent a success, is whether or not the parasitoids will similarly impact nativestink bug species. Not all stink bugsin Oregon are bad, and researchers wantto make sure non-target species won’t be affected.

“We’vemade strong progress this past year in establishing the colonies,” says ODAentomologist Barry Bai, who is working with an OSU graduate student to conductthe research. “Ourgoal right now is to test native species to make sure the parasitoidswon’t go after them. It’s a long process. We need to test several generationsof parasitoids to make sure they don’t affect the goodstink bugs andefficiently deal with the bad ones.”

WhileODA and its cooperators test out the biocontrol agent on non-target speciesthis summer, similar work is being done in Michigan and Florida with nativestink bugs in their respectiveregions. All data will be shared and evaluatedbefore any final decision is made to allow release of the tiny wasps.

Assumingthe imported parasitoids impact only the brown marmorated stink bugeggs, theywould be reared in insectaries to attain sufficient numbers and possibly bereleased into the natural environment within the next couple of years.

“Maybeby 2015, there will be some limited, restricted field releases by ARS,” saysRogg.

Otherimported natural enemies of the brown marmorated stink bug are also underconsideration. Everyone wants to see how promising the first biocontrol agentis before moving onto thenext one. It could be that a combination ofparasitoids will be necessary to control the bad stink bug.

ODAsuccessfully conducted similar research on biocontrol agents for cereal leafbeetle before the good bugs were released in crop production areas. They arecurrently doing a good jobcontrolling that pest.

“We’vedone this sort of thing before,” says Rogg. “If it all works out, there is hopedown the road that these parasitoids will help keep brown marmorated stink bugunder control. It’s really adifficult pest. There is no monitoring tool astraps don’t seem to work. There appears to be no other good control tool,including pesticides. So the big hope is for biological control.”

Thefirst tool in the tool box may be the tiny wasp currently being tested in aquarantine facility in Corvallis. In a best case scenario, the parasitoid willtake up permanent residency in Oregonto control the brown marmorated stink bugfor years to come.